Hi,
I've tried out the emissive maps and they work great except they don't actually "glow", which is kind of necessary for my game. I've heard about using the HDR to make it more glowy, but I don't think that's quite the effect I'm looking for. The other method I've seen is to render the objects to another target then apply a blur post processor on top of that, but I don't want the entire model to blur. So do I need a shader to just render the glow maps and then apply a blur on to that? Also, if it helps, I'm using deferred rendering on 2.0.17 Pro.
Here's a reference image:
http://pseudosynthesis.com/p/posts/emissive_map-1.png
I'm not sure if it's quite the look you're going for, but one way to make things glow is to use an emissive map and a point light that's very short range, has low intensity, and is set to your "glow color". This tends to give off the illusion that your object is glowing.
Now if you want more of a hazy glow look, then I'd suggest doing the same thing but also adding either a light particle effect and/or using HDR post processing.
Nate
Oh yeah, sorry, I should have explained that better. I plan on using the point light idea, but the hazy look is what I'm working on.
I don't see how I can get HDR to really give me that effect, but I can try that out more. Could you explain the "light particle effect", I've never heard of that.
I think my wording may have been a little confusing, I meant light as in lightweight, not light as in an actual light. :)
The effect I'm thinking of is similar to what can be seen in games sometimes for objects like streetlights. Basically the particle texture you'd use is just a simple white circle that's solid in the center and then has its alpha fade out as you go towards the edges of the texture. The particle effect itself is static (or mostly static), and then you just have it set to AlphaBlend and toss its transparency down to about 25% (or whatever looks good). That's one way to do it, and in your case I'd also tint the particle effect to match your emissive color.
How well HDR works tends to depend on how much of a contrast there is between objects you don't want to glow and objects you do want to glow. If everything in your scene is a very similar color, then you'll usually get more of a blur effect than a glow effect.
Oh, I see. A particle system wouldn't work for what I'm doing because my emissive maps can have designs in them which would need to glow in that shape.
It sounds like I'll have to use HDR. Do you know of a way I can make the HDR more effective on just the objects I want to glow? It seems like in order to make it as intense as I'd like, it would make my entire scene way too bloomy.
Hm, well if your glowing textures have a similar color than your non-glowing textures, then yeah everything in your scene will probably either become too blurry or have too much bloom.
Maybe you could try lowering the ambient light in your scene (or any other main lights you might have in your scene). If your scene's darker, the emissive textures should stand out more, which should make it easier to have them glow without other things glowing as well.
I've been trying to use HDR, but it's really just not working for my type of scenes I think. I need to be able to have the room light enough to have things visible but if something is in the dark it should have the glowing effect. Here's an example of that: http://pseudosynthesis.com/p/posts/emissive_map_hdr-1.png
The only thing I want to glow in my scene is the dots on the mushroom model's emissive map, but that's the only thing that's not glowing. Is there some way to get the settings to do that, or do I need to find a different way to get the effect I want?
Looking at things some more, I'm not sure if the built-in HDR can do exactly what you want it to do, because the glow effects you essentially want are what this article talks about (it's a bit old but it does have some nice theory):
http://www.gamasutra.com/view/feature/2107/realtime_glow.php?page=1
So HDR is what you want, but you might have to make your own custom version (or base it off of the App Hub's bloom example):
http://create.msdn.com/en-US/education/catalog/sample/bloom
Also, I'd suggest checking out this post as there's some additional useful info on object glow:
http://forums.create.msdn.com/forums/p/65328/400578.aspx
You may also be interested by these 2 post processors:
Hey, just wanted to post back with my results for others who run into the same problem. Thanks to your help I was able to solve it.
I ended up rendering models' emissive maps to another render target, then saturating it and blurring it using shaders. To solve the issue of having the glow go through walls I rendered my level at the same time as the glowing models, but just as black. Then in a shader I made any pixel just black (which would be everything except for the glowing parts) have an alpha of 0.
It still needs tweaking, but here's an example of what it looks like: http://pseudosynthesis.com/p/posts/emissive_map_glow-2.png
Nice, glad I could help.
JacKAsterisK: It still needs tweaking, but here's an example of what it looks like: http://pseudosynthesis.com/p/posts/emissive_map_glow-2.png
Looks good!